Microbiology Lab Final Review Flashcards

Vocabulary-based flashcards for the Microbiology Lab Final, covering staining techniques, microscope use, biochemical tests, media, and microbial quantification.

Proper Scientific Naming

The genus name is capitalized, the species name is lowercase, and both names are either underlined or italicized.

4x Scanning Objective

The smallest microscope objective, usually marked with a red ring.

10x Low Power Objective

A microscope objective usually marked with a yellow ring.

40x High Power / High Dry Objective

A microscope objective used for high-dry magnification without oil.

100x Oil Immersion Objective

A microscope objective usually marked with a white ring that requires oil for clarity.

Total Magnification

Calculated by multiplying the ocular magnification ($10\times$) by the objective magnification ($4\times$, $10\times$, $40\times$, or $100\times$).

Resolving Power

The ability of a microscope to distinguish detail and structure; for a compound light microscope, this is $0.2\text{\thinspace}\mu m$ or $200\text{\thinspace}nm$.

Heat Fixing

The process of running a totally air-dried bacterial smear through a Bunsen burner flame 3 times to fix the organisms to the slide.

Simple Stain

A staining technique using a basic (positive) dye to give bacteria color to determine morphology, shape, and arrangement.

Negative Stain

A technique using an acidic (negative) dye where the negatively charged chromophore is repelled by the cell, resulting in a colorless cell and a stained background.

Differential Staining

Techniques such as Gram, endospore, or acid-fast stains used to identify specific structures or cell wall compositions.

Methylene Blue

A basic dye used for simple staining in Exercise 2.

Congo Red

An acidic dye used for negative staining in Exercise 2 or as a primary stain in capsule staining.

Mycolic Acid

A waxy substance found in the cell walls of acid-fast bacteria like Mycobacterium.

Crystal Violet

The primary stain used in the Gram staining procedure.

Gram's Iodine

The mordant used in Gram staining that helps the primary stain stick to the cell.

95% Ethanol

The decolorizer used in the Gram staining procedure; it must be applied drop by drop until clear.

Safranin

The counterstain used in both Gram staining and endospore staining to color colorless cells pink/red.

Gram-Positive Cell Wall

Characterized by a thick layer of peptidoglycan and teichoic acids.

Gram-Negative Cell Wall

Characterized by a thin layer of peptidoglycan and a lipopolysaccharide outer membrane.

Malachite Green

The primary stain specifically used in the endospore staining procedure.

Vegetative Cell

An actively growing bacterial cell that appears pink in an endospore stain.

Endospore

A dormant, resistant structure that appears green in an endospore stain.

SIM Tube

A multi-test medium used to detect Sulfur reduction ($H_2S$ production), Indole production, and Motility.

Indole Production

Measured by adding Kovac's reagent; a positive result is indicated by a pinkish-red ring at the top of the tube.

Ubiquity of Microorganisms

The principle that organisms are everywhere, necessitating the use of aseptic techniques.

Carbolfuchsin

The primary stain used in the acid-fast staining procedure; it stains acid-fast cells pink.

Acid-Alcohol

The decolorizer used in the acid-fast staining procedure.

Streptococci Arrangement

Bacterial cells arranged in chains of cocci.

Staphylococci Arrangement

Bacterial cells arranged in clusters of cocci.

Amylase

An enzyme that digests starch; production is confirmed by a clearing around growth on a starch plate after adding iodine.

DNAse

An enzyme that digests DNA; confirmed by a clearing on a DNA plate.

Catalase

An enzyme that breaks down hydrogen peroxide; a positive test is indicated by immediate bubbling.

Urease

An enzyme that digests urea; a positive test is indicated by the medium turning hot pink.

Yeast

A type of fungus that is larger than bacteria, oval-shaped, and may show budding.

Mold

A type of fungus characterized by branchlike hyphae and attached spores.

Beta Hemolysis

Complete hemolysis on a blood agar plate, resulting in a clear zone around the colonies.

Alpha Hemolysis

Partial hemolysis resulting in a greenish tint around the colonies on blood agar.

Gamma Hemolysis

No hemolysis of red blood cells on a blood agar plate.

Mannitol Salt Agar (MSA)

Media that is selective for halophiles (due to high salt) and differential for mannitol fermentation (yellow indicates acid production).

MacConkey Agar (MAC)

Media selective for Gram-negative enterics (contains bile/crystal violet) and differential for lactose fermentation (pink indicates positive).

Eosin Methylene Blue (EMB)

Media selective for Gram-negative enterics; lactose fermenters appear pink or metallic green.

Zone of Inhibition

The clear area around an antibiotic disc where growth is prevented, measured in millimeters to determine susceptibility.

Plaques

Clearings in a bacterial lawn caused by bacteriophages (viruses) lysing the host cells.

Countable Plate Range

A plate containing between $30$ and $300$ colonies (CFU) or plaques (PFU).

TFTC

Too Few To Count (less than $30$).

TMTC / TNTC

Too Many To Count or Too Numerous To Count (greater than $300$).